use versionned css

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1551849 13f79535-47bb-0310-9956-ffa450edef68
[MRM-1789] Register link appears after logging in and back out even "Disable registration Link" is checked

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1551850 13f79535-47bb-0310-9956-ffa450edef68